Biolubricant esters from the alcohols of unsaturated fatty acids

ABSTRACT

The present invention is generally directed to triester-based lubricant compositions. The present invention is also directed to methods of making these and other similar lubricant compositions. In some embodiments, the methods for making such triester-based lubricants utilize a biomass precursor comprising mono-unsaturated fatty acids, wherein such mono-unsaturated fatty acids are reduced to mono-unsaturated fatty alcohols en route to the synthesis of triester species for use as/in the triester-based lubricant compositions. Subsequent steps in such synthesis may employ carboxylic acids and/or acyl halides/anhydrides derived from biomass and/or Fischer-Tropsch synthesis.

PRIORITY TO RELATED APPLICATIONS

This application is a divisional application of co-pending applicationof U.S. Ser. No. 12/316,209, filed Jun. 8, 2009 and claims prioritythereto.

FIELD OF THE INVENTION

This invention relates to ester-based lubricants and specifically totriester-based lubricants and their manufacture—particularly whereinthey are made from at least one biologically-derived precursor.

BACKGROUND

Esters have been used as lubricating oils for over 50 years. They areused in a variety of applications ranging from jet engines torefrigeration. In fact, esters were the first synthetic crankcase motoroils in automotive applications. However, esters gave way topolyalphaolefins (PAOs) due to the lower cost of PAOs and theirformulation similarities to mineral oils. In full synthetic motor oils,however, esters are almost always used in combination with PAOs tobalance the effect on seals, additives solubility, volatility reduction,and energy efficiency improvement by enhanced lubricity.

Ester-based lubricants, in general, have excellent lubricationproperties due to the polarity of the ester molecules of which they arecomprised. The polar ester groups of such molecules adhere topositively-charged metal surfaces creating protective films which slowdown the wear and tear of the metal surfaces. Such lubricants are lessvolatile than the traditional lubricants and tend to have much higherflash points and much lower vapor pressures. Ester-based lubricants areexcellent solvents and dispersants, and can readily solvate and dispersethe degradation by-products of oils. Therefore, they greatly reducesludge buildup. While ester-based lubricants are stable to thermal andoxidative processes, the ester functionalities give microbes a handle todo their biodegrading more efficiently and more effectively than theirmineral oil-based analogues. However, the preparation of esters is moreinvolved and more costly than the preparation of their PAO counterparts.

Triester-based lubricants and their manufacture have been recentlyreported, wherein the triester species have a general formula:

where R₁₋₄ are the same or independently selected from C₂ to C₂₀hydrocarbon groups, and n is an integer from 2 to 20. Seecommonly-assigned U.S. patent application Ser. No. 12,122,894; filedApr. 4, 2007 and published as United States Patent Publication No.20080248982. Note that the ester group comprising R₂ is attached to thealiphatic backbone via an inverted (non-homologous) linkage (compared tothe ester groups comprising R₃ and R₄).

In view of the foregoing, and not withstanding such above-describedadvances in triester-based lubricant synthesis, facile methods ofgenerating triester-based lubricants would be extremelyuseful—particularly wherein the triester species in said lubricantscomprise homologous linkages between all three ester groups and thealiphatic backbone.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is generally directed to triester-based lubricantcompositions. The present invention is also directed to methods ofmaking these and other similar lubricant compositions. In someembodiments, the methods for making such triester-based lubricants atleast partially make use of one or more biomass precursors. In these orother embodiments, lubricant precursor species can also be sourced orderived from Fischer-Tropsch (FT) reaction products/byproducts.

In some embodiments, the present invention is directed to a lubricantcomposition comprising a quantity of at least one triester species, thetriester species having the following structure:

wherein R₁, R₂, R₃, and R₄ are the same or independently selected fromC₂ to C₂₀ hydrocarbon groups, and wherein “n” is a number from 2 to 20.

In some embodiments, the kinematic viscosity of the above-describedcomposition at a temperature of 100° C. is at least 3 mm²/s, i.e.,centistokes (cSt). In some or other embodiments, said composition has apour point of less than −20° C.

For the above-described composition, R₁ is typically selected to have atotal carbon number of from at least about 6 to at most about 12, R₃ andR₄ are typically selected to have a combined carbon number from at leastabout 2 to at most about 40, R₂ is typically selected to have a carbonnumber from at least about 1 to at most about 20, and “n,” as denoted in—(CH₂)_(n)— in the above structure, is typically an integer in the rangeof from at least about 5 to at most about 10. Typically, for thelubricant composition described above, the at least one triester specieshas a molecular mass that is from at least about 400 atomic mass units(a.m.u.) to at most about 1100 a.m.u. More typically, the at least onetriester species has a molecular mass that is from at least about 450a.m.u. to at most about 1000 a.m.u.

In some embodiments, at least one triester species in theabove-described lubricant composition is selected from the groupconsisting of octadecane-1,9,10-triyl trihexanoate (1);octadecane-1,9,10-triyl triheptanoate; octadecane-1,9,10-triyltrioctanoate (2); octadecane-1,9,10-triyl trinonoate;octadecane-1,9,10-triyl tris(decanoate) (3); octadecane-1,9,10-triyltridodecanoate (4); octadecane-1,9,10-triyl triundecanoate;octadecane-1,9,10-triyl tridodecanoate; octadecane-1,9,10-triyltridecanoate; and octadecane-1,9,10-triyl tritetradecanoate (5); andmixtures thereof. For corresponding structures of compounds 1-5, seeFIG. 1 (vide infra).

In some embodiments, the above-described composition comprisesquantities of at least two different triester species. In some or otherembodiments, said composition further comprises a base oil selected fromthe group consisting of Group I oils, Group II oils, Group III oils, andcombinations thereof. Additionally or alternatively, in someembodiments, said composition further comprises one or more diesterspecies.

In some embodiments, the present invention is directed to methods ofmaking the above-described composition(s), such methods comprising thesteps of: (a) reducing a mono-unsaturated fatty acid having a carbonnumber of from 10 to 22 with a metal hydride so as to form anunsaturated fatty alcohol; (b) epoxidizing the unsaturated fatty alcoholto form an epoxy-alcohol species comprising an epoxide ring; (c) openingthe ring of the epoxy-alcohol species to form a triol; and (d)esterifying the triol with an esterifying species to form a triesterspecies, wherein the esterifying species is selected from the groupconsisting of carboxylic acids, acyl halides, acyl anhydrides, andcombinations thereof, and wherein the esterifying species have a carbonnumber of from 2 to 18. In some such embodiments, said method can yielda mixture of triester species within the resulting lubricant compositionby utilizing, in one or both of steps (a) and (d), reagents (e.g.,mono-unsaturated fatty acids and esterifying species) that comprise arange of carbon number.

In some embodiments, such above-described methods further comprise astep of blending the triester species with other triester species. Insome or other embodiments, such methods can further comprise a step ofblending the triester species with one or more diester species. In someor still other embodiments, such methods can further comprise a step ofblending the triester species with a base oil selected from the groupconsisting of Group I oils, Group II oils, Group III oils, andcombinations thereof.

In some particular embodiments, wherein the above-described method usesoleic acid as a representative mono-unsaturated fatty acid, theresulting triester is of the type:

wherein R₂, R₃ and R₄ are typically the same or independently selectedfrom C₂ to C₂₀ hydrocarbon groups, and are more typically selected fromC₄ to C₁₂ hydrocarbon groups.

The foregoing has outlined rather broadly the features of the presentinvention in order that the detailed description of the invention thatfollows may be better understood. Additional features and advantages ofthe invention will be described hereinafter which form the subject ofthe claims of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts five exemplary triester-based compounds 1-5, suitable foruse as lubricants and/or lubricant components, in accordance with someembodiments of the present invention;

FIG. 2 (Scheme 1) is a chemical flow diagram generally illustratingmethods of making a triester-based lubricant composition, in accordancewith some embodiments of the present invention, wherein oleic acid isused as a representative mono-unsaturated fatty acid;

FIG. 3 (Scheme 2) is a chemical flow diagram illustrating an exemplarymethod of making triester composition 1, in accordance with someembodiments of the present invention; and

FIG. 4 (Table 1) tabularizes lubrication properties of triester species1.

DETAILED DESCRIPTION OF THE INVENTION 1. Introduction

The present invention is generally directed to triester-based lubricantcompositions. The present invention is also directed to methods ofmaking these and other similar lubricant compositions. In many of theseembodiments, the methods for making such triester-based lubricantsutilize a biomass precursor, wherein it is typically at least the fatty(carboxylic) acids utilized in such methods that are obtained frombiomass sources (e.g., vegetable oil and/or algae). Other chemicalcomponents used in such methods can be derived from biomass or othersources such as, but not limited to, Fischer-Tropsch (FT) synthesisproducts and/or by-products.

Because biolubricants and biofuels are increasingly gaining ground andbecoming topics of focus for many in the oil industry, the use ofbiomass in the making of such above-mentioned lubricants could beattractive from several different perspectives. To the extent thatbiomass is so utilized in making the triester-based lubricants of thepresent invention, such lubricants are deemed to be biolubricants.

An advantage of the tri-ester lubricants described herein in at leastsome embodiments is that they can be entirely bio-derived, i.e., all ofthe reagents used in their synthesis (exclusive of solvents andcatalysts) can be derived from a biological precursor material.Additionally, methods for producing such lubricants make use of theolefins already present in vegetable/crop oils, thereby streamlining thesynthetic process. Additionally still, as opposed to conventionaltriester biolubricants, i.e., triglycerides, the tri-ester lubricantsdescribed herein in at least some embodiments generally have excellentlow temperature properties without having carbon-carbon double bonds(which would compromise oxidation stability).

2. Definitions

“Lubricants,” as defined herein, are substances (usually a fluid underoperating conditions) introduced between two moving surfaces so toreduce the friction and wear between them. Base oils used as motor oilsare generally classified by the American Petroleum Institute as beingmineral oils (Group I, II, and III) or synthetic oils (Group IV and V).See American Petroleum Institute (API) Publication Number 1509.

“Pour point,” as defined herein, represents the lowest temperature atwhich a fluid will pour or flow. See, e.g., ASTM Standard Test Method D5950-02 (R 2007).

“Cloud point,” as defined herein, represents the temperature at which afluid begins to phase separate due to crystal formation. See, e.g., ASTMStandard Test Method D 5771-05.

“Centistoke,” abbreviated “cSt,” is a unit for kinematic viscosity of afluid (e.g., a lubricant), wherein 1 centistoke equals 1 millimetersquared per second (1 cSt=1 mm²/s). See, e.g., ASTM Standard Guide andTest Method D 2270-04.

“Oxidation stability,” as defined herein, generally refers to acomposition's resistance to oxidation. Oxidator BN is a convenient wayto measure the oxidation stability of base oils, and it is the methodused to evaluate the oxidation stability of at least some of thelubricant compositions described herein. The Oxidator BN test isdescribed by Stangeland et al. in U.S. Pat. No. 3,852,207. The OxidatorBN test measures an oil's resistance to oxidation by means of aDornte-type oxygen absorption apparatus. See Dornte “Oxidation of WhiteOils,” Industrial and Engineering Chemistry, vol. 28, pp. 26-30, 1936.Normally, the conditions are one atmosphere of pure oxygen at 340° F.(171° C.). The results are reported in hours to absorb 1000 mL (1 L) ofO₂ by 100 grams of oil.

With respect to describing molecules and/or molecular fragments herein,“R_(m),” where “m” is merely an identifier, refers to a hydrocarbongroup, wherein the molecules and/or molecular fragments can be linearand/or branched, and unless stated otherwise, groups identified bydifferent “m” identifiers can be the same or different.

As defined herein, “carbon number,” as it relates to a hydrocarbonmolecule or fragment (e.g., an alkyl group), is an integer denoting thetotal number of carbon atoms in the fragment or molecule. Carbon numberwith such a fragment or molecule can also be denoted as “C_(n)”, where“n” is the total number of carbon atoms within that particular fragmentor molecule.

The prefix “bio,” as used herein, refers to an association with arenewable resource of biological origin, such as resource generallybeing exclusive of fossil fuels.

“Fischer-Tropsch products,” as defined herein, refer to molecularspecies derived from a catalytically-driven reaction between CO and H₂(i.e., “syngas”). See, e.g., Dry, “The Fischer-Tropsch process:1950-2000,” vol. 71(3-4), pp. 227-241, 2002; Schulz, “Short history andpresent trends of Fischer-Tropsch synthesis,” Applied Catalysis A, vol.186, pp. 3-12, 1999.

3. Triester Lubricant Compositions

In some embodiments, the present invention is generally directed totriester-based lubricant compositions comprising a quantity of triesterspecies having the following chemical structure:

wherein R₁, R₂, R₃, and R₄ are the same or independently selected fromC₂ to C₂₀ hydrocarbon groups (groups with a carbon number from 2 to 20),and wherein “n” is an integer from 2 to 20.

Regarding the above-mentioned triester species, selection of R₁, R₂, R₃,R₄, and n can follow any or all of several criteria. For example, insome embodiments, R₁, R₂, R₃, R₄ and n are selected such that thekinematic viscosity of the composition at a temperature of 100° C. istypically 3 mm²/s, i.e., centistokes (cSt) or greater. In some or otherembodiments, R₁, R₂, R₃, R₄ and n are selected such that the pour pointof the resulting lubricant is −20° C. or lower. In some embodiments, R₁is selected to have a total carbon number of from 6 to 12. In these orother embodiments, R₂ is selected to have a carbon number of from 1 to20. In these or other embodiments, R₃ and R₄ are selected to have acombined carbon number of from 4 to 36. In these or other embodiments, nis selected to be an integer from 5 to 10. Depending on the embodiment,such resulting triester species can typically have a molecular massbetween 400 atomic mass units (a.m.u.) and 1100 a.m.u, and moretypically between 450 a.m.u. and 1000 a.m.u.

In some embodiments, such above-described compositions are substantiallyhomogeneous in terms of their triester component. In some or otherembodiments, the triester component of such compositions comprises avariety (i.e., a mixture) of such triester species. In these or otherembodiments, such above-described lubricant compositions furthercomprise one or more diester species.

Referring to FIG. 1, in some of the above-described embodiments, thetriester-based lubricant composition comprises one or more of theexemplary triester species shown, i.e., one or more of the following:octadecane-1,9,10-triyl trihexanoate (1); octadecane-1,9,10-triyltriheptanoate; octadecane-1,9,10-triyl trioctanoate (2);octadecane-1,9,10-triyl trinonoate; octadecane-1,9,10-triyltris(decanoate) (3); octadecane-1,9,10-triyl tridodecanoate (4);octadecane-1,9,10-triyl triundecanoate; octadecane-1,9,10-triyltridodecanoate; octadecane-1,9,10-triyl tridecanoate; andoctadecane-1,9,10-triyl tritetradecanoate (5). In some embodiments, thetriester-based lubricant composition further comprises a base oilselected from the group consisting of Group I oils, Group II oils, GroupIII oils, and mixtures thereof.

It is worth noting that in many applications, the above-describedtriesters and their compositions are not used as lubricants bythemselves, but are used as blending stocks. As such, esters with higherpour points may also be used as blending stocks with other lubricantoils since they are very soluble in hydrocarbons and hydrocarbon-basedoils.

4. Methods of Making Triester Lubricants

As mentioned above, the present invention is additionally directed tomethods of making the above-described lubricant compositions and/or thetriester compositions contained therein.

Referring to the chemical flow diagram shown in FIG. 2 (Scheme 1), insome embodiments, processes/methods for making the above-mentionedtriester-based compositions, typically having lubricating base oilviscosity and pour point, comprise the following steps: (Step 201)reducing a mono-unsaturated fatty acid (6) having a carbon number offrom 10 to 22 with a metal hydride so as to form an unsaturated fattyalcohol (7); (Step 202) epoxidizing the unsaturated fatty alcohol 7 toform an epoxy-alcohol species (8) comprising an epoxide ring; (Step 203)opening the ring of the epoxy-alcohol species 8 to form a triol (9); and(Step 204) esterifying the triol 9 with an esterifying species (10) toform a triester species (11), wherein the esterifying species 10 isselected from the group consisting of carboxylic acids, acyl halides,acyl anhydrides, and combinations thereof, and wherein the esterifyingspecies have a carbon number of from 2 to 18. In some such embodiments,said method can yield a mixture of triester species within the resultinglubricant composition by utilizing, in one or both of Steps 201 and 204,reagents that comprise a range of carbon number.

Generally, lubricant compositions made by such methods and comprisingsuch triester species have a viscosity of 3 mm²/s (centistokes) or moreat a temperature of 100° C. and they typically have a pour point of lessthan −20° C., and selection of reagents and/or mixture components istypically made with this objective.

In some embodiments, where a quantity of such triester species isformed, the quantity of triester species can be substantiallyhomogeneous, or it can be a mixture of two or more different suchtriester species. In any such embodiments, such triester compositionscan be further mixed with one or more base oils of the type Group I-III.Additionally or alternatively, in some embodiments, such methods furthercomprise a step of blending the triester composition(s) with one or morediester and/or monoester species. In some such additional and/oralternative embodiments, some or all of the one or more diester speciesare as described in commonly-assigned U.S. patent Ser. No. 11/673,879;filed Feb. 12, 2007 and published as United States Patent PublicationNo. 20080194444.

In some embodiments, such methods produce compositions (vide supra)comprising at least one triester species selected from among thefollowing: octadecane-1,9,10-triyl trihexanoate (1);octadecane-1,9,10-triyl triheptanoate; octadecane-1,9,10-triyltrioctanoate (2); octadecane-1,9,10-triyl trinonoate;octadecane-1,9,10-triyl tris(decanoate) (3); octadecane-1,9,10-triyltridodecanoate (4); octadecane-1,9,10-triyl triundecanoate;octadecane-1,9,10-triyl tridodecanoate; octadecane-1,9,10-triyltridecanoate; and octadecane-1,9,10-triyl tritetradecanoate (5); andmixtures thereof.

In some such above-described method embodiments, the mono-unsaturatedfatty acid can be a bio-derived fatty acid formed by hydrolysis of oneor more triglyceride-containing vegetable oils such as, but not limitedto, palm oil, sunflower oil, rapeseed oil, olive oil, linseed oil, andthe like. Other sources of triglycerides, for which hydrolysis can yieldunsaturated fatty acids, include, but are not limited to, algae, animaltallow, and zooplankton. See, e.g., Bajpai et al., “Biodiesel: Source,Production, Composition, Properties and Its Benefits,” J. Oleo Sci.,vol. 55(10), pp. 487-502, 2006 (general review); Sargent et al.,“Biosynthesis of Lipids in Zooplankton from Saanich Inlet, BritishColumbia, Canada,” Marine Biology, vol. 31, pp. 15-23, 1975 (zooplanktonas a source of lipids).

In some embodiments, wherein the above-mentioned hydrolyzed triglyceridesources contain mixtures of saturated fatty acids, mono-unsaturatedfatty acids, and poly-unsaturated fatty acids, one or more techniquesmay be employed to isolate, concentrate, or otherwise separate themono-unsaturated fatty acids from the other fatty acids in the mixture.See, e.g., commonly-assigned United States patent application by Millerentitled, “Isolation and Subsequent Utilization of Saturated Fatty Acidsand α-Olefins in the Production of Ester-Based Biolubricants,” Ser. No.12/122,894, filed May 19, 2008.

In some embodiments, partial hydrogenation of polyunsaturated fattyacids can yield mono-unsaturated fatty acids for use in methods of thepresent invention. Post hydrogenation, such mono-unsaturated fatty acidsmay be subjected to one or more of the above-mentionedseparation/isolation techniques. See, e.g., Falk et al., “The Effect ofFatty Acid Composition on Biodiesel Oxidative Stability,” Eur. Journalof Lipid Sci. & Technol., vol. 106(12), pp. 837-843, 2004.

Regarding the step of metal-hydride reduction, in some embodiments,lithium aluminum hydride (LiAlH₄) is used as the reducing agent. In someor other embodiments, particularly for industrial-scale processes,catalytic hydrogenation is employed using, for example, copper- orzinc-based catalysts. See, e.g., U.S. Pat. No. 4,880,937; Scrimgeour,“Chemistry of Fatty Acids,” in Bailey's Industrial Oil and Fat Products,6^(th) Edition, Vol. 1, pp. 1-43, F. Shahidi (Ed.), J. Wiley & Sons, NewYork, 2005.

Regarding the step of epoxidizing (i.e., the epoxidation step), in someembodiments, the above-described unsaturated fatty alcohol can bereacted with a peroxide (e.g., H₂O₂) or a peroxy acid (e.g.,peroxyacetic acid) to generate an epoxy-alcohol species. See, e.g.,Swern et al., “Epoxidation of Oleic Acid, Methyl Oleate and OleylAlcohol with Perbenzoic Acid,” J. Am. Chem. Soc., vol. 66(11), pp.1925-1927, 1944.

Regarding the step of epoxide ring opening to the corresponding triol,this step can involve an acid-catalyzed hydrolysis. Exemplary acidcatalysts include, but are not limited to, mineral-based Brönsted acids(e.g., HCl, H₂SO₄, H₃PO₄, perhalogenates, etc.), Lewis acids (e.g.,TiCl₄ and AlCl₃), solid acids such as acidic aluminas and silicas ortheir mixtures, and the like. See, e.g., Parker et al., “Mechanisms ofEpoxide Reactions,” Chem. Rev., vol. 59(4), pp. 737-799, 1959; andPaterson et al., “meso Epoxides in Asymmetric Synthesis:Enantioselective Opening by Nucleophiles in the Presence of Chiral LewisAcids,” Angew. Chem. Int. Ed., vol. 31(9), pp. 1179-1180, 1992. Theepoxide ring opening to the diol can also be accomplished bybase-catalyzed hydrolysis using, for example, aqueous solutions of KOHor NaOH.

Regarding the step of esterifying the triol to form a triester, an acidcan be used to catalyze the reaction between the —OH groups of the dioland the carboxylic acid(s). Suitable acids include, but are not limitedto, sulfuric acid (Munch-Peterson, Org Synth., Coll. Vol. 5, p. 762,1973), sulfonic acid (Allen and Sprangler, Org Synth., Coll. Vol. 3, p.203, 1955), hydrochloric acid (Eliel et al., Org Synth., Coll. Vol. 4,p. 169, 1963), and phosphoric acid (among others). In some embodiments,the carboxylic acid used in this step is first converted to an acylchloride (or another acyl halide) via, e.g., thionyl chloride or PCl₃.Alternatively, an acyl chloride (or other acyl halide) could be employeddirectly. Where an acyl chloride is used, an acid catalyst is not neededand a base such as pyridine, 4-dimethylaminopyridine (DMAP) ortriethylamine (TEA) is typically added to react with an HCl produced.When pyridine or DMAP is used, it is believed that these amines also actas a catalyst by forming a more reactive acylating intermediate.Accordingly, such esterification steps can also be base-catalyzed. See,e.g., Fersht et al., “Acetylpyridinium ion intermediate inpyridine-catalyzed hydrolysis and acyl transfer reactions of aceticanhydride. Observation, kinetics, structure-reactivity correlations, andeffects of concentrated salt solutions,” J. Am. Chem. Soc., vol. 92(18),pp. 5432-5442, 1970; and Höfle et al., “4-Dialkylaminopyradines asHighly Active Acylation Catalysts,” Angew. Chem. Int. Ed. Engl., vol.17, pp. 569-583, 1978. Additionally or alternatively, the carboxylicacid could be converted into an acyl anhydride and/or such species couldbe employed directly.

Regardless of the source of the mono-unsaturated fatty acid (videsupra), in some embodiments, the carboxylic acids (or their acylderivatives) used in the above-described methods are derived frombiomass. In some such embodiments, this involves the extraction of someoil (e.g., triglyceride) component from the biomass and hydrolysis ofthe triglycerides of which the oil component is comprised so as to formfree carboxylic acids. Other sources of such carboxylic acids include,but are not limited to, those derived (directly or indirectly) from FTsynthesis.

5. Variations

Variations on the above-described methods include, but are not limitedto, generating (and utilizing) compositional ranges of triesters byblending and/or by compositional variation in the reagents used duringthe synthesis of the triester species described herein. Compositionsproduced by such method variations will, naturally, be variationsthemselves. Generally, all such variations fall within the scope of thecompositions and methods described herein.

In some variational embodiments, molecular averaging can be employed togenerate greater molecular homogeneity in the resulting compositions (atleast in terms of the triester species contained therein). Suchmolecular averaging techniques involve olefin metathesis and aregenerally described in the following U.S. Pat. Nos. 6,566,568;6,369,286; and 6,562,230.

In some or other variational embodiments, the olefinic portion of themono-unsaturated fatty alcohol can be efficiently transformed to thecorresponding triol by highly selective reagents such as osmiumtetra-oxide (M. Schroder, “Osmium tetraoxide cis hydroxylation ofunsaturated substrates,” Chem. Rev., vol. 80(2), pp. 187-213, 1980) andpotassium permanganate (Sheldon and Kochi, in Metal-Catalyzed Oxidationof Organic Compounds, pp. 162-171 and 294-296, Academic Press, New York,1981).

In some or still other variational embodiments, the sequence of reactionsteps in producing the triol species can be modified as described, e.g.,in Example 3 (vide infra).

6. Examples

The following examples are provided to demonstrate particularembodiments of the present invention. It should be appreciated by thoseof skill in the art that the methods disclosed in the examples whichfollow merely represent exemplary embodiments of the present invention.However, those of skill in the art should, in light of the presentdisclosure, appreciate that many changes can be made in the specificembodiments described and still obtain a like or similar result withoutdeparting from the spirit and scope of the present invention.

As an exemplary synthetic procedure, the synthesis of triester 1 (Scheme2, FIG. 3) is described in Examples 1-4. This procedure isrepresentative for making triesters from mono-unsaturated fatty acids,in accordance with some embodiments of the present invention.

Example 1

This Example serves to illustrate synthesis of oleoyl alcohol 7 (anexemplary monounsaturated fatty acid), via a reduction of oleic acid(Step 201 a), en route to synthesis of exemplary triester 1 and inaccordance with some embodiments of the present invention. Oleoylalcohol 7 was prepared according to the following procedure.

To an ice-cold (ice bath) suspension of 43 grams (1.13 mol) of lithiumaluminum hydride (LiAlH₄) in tetrahydrofuran (THF) in a 3-neck 3-literreaction flask fitted with an overhead stirrer and a reflux condenser,150 grams (0.53 mol) of oleic acid 6 was added drop-wise over a periodof 45 minutes via an addition funnel. The resulting reaction mixture wasallowed to warm gradually to room temperature, after which the ice bathwas replaced with a heating mantle and the reaction mixture was refluxedfor 4 hours. After reflux, the reaction mixture was allowed to cool toroom temperature and stirred overnight. The reaction progress wasmonitored by infrared (IR) and nuclear magnetic resonance (NMR)spectroscopies for the disappearance of the acid carbonyl group. Thereaction was worked up by dilution with 500 mL diethyl ether followed byslow addition (drop-wise) of 350 mL of 15 wt % NaOH aqueous solution at0° C. with vigorous stirring followed by the addition of 50 mL of water.The resulting 2-layer solution, a white solid precipitate and clearorganic layer, was filtered to remove the solids (i.e., the unwantedinorganic salts). The organic layer was dried over anhydrous MgSO₄,filtered and concentrated on a rotary evaporator to give themono-unsaturated fatty alcohol as a colorless oil. The reaction afforded133 grams (93%) of the desired oleoyl alcohol 7. The product wasauthenticated with NMR, IR, and gas-chromatography/mass spectrometric(GC/MS) analyses.

Example 2

This Example serves to illustrate the synthesis of theoctadecane-1,9,10-triol 9 (an exemplary triol) (Steps 202 a and 203 a),en route to the synthesis of triester species 1 and in accordance withsome embodiments of the present invention. The triol 9 was preparedaccording to the following procedure.

To an ice-cold solution of hydrogen peroxide (110 grams of 30 wt % H₂O₂)and formic acid (250 grams of 88 wt % HCO₂H) in a 1 L, 3-neck reactionflask, 130 grams of oleoyl alcohol 7 (prepared as described in Example 1above) were added drop-wise over 45 minutes. Once the addition wascomplete, the reaction was allowed to slowly warm to room temperatureand then heated to 40° C. for 3 hours. The reaction was subsequentlyallowed to stir over night at room temperature. The reaction wasstripped on a rotary evaporator to remove excess formic acid. Theresidual mixture of the triol 9 and its formates was treated with an icecold solution of sodium hydroxide (45 grams NaOH in 100 grams water) insmall portions. The addition was done slowly and carefully and thetemperature was kept around 40° C. Once the addition of NaOH wascompleted, the mixture was diluted with 500 mL ethyl acetate and heatedto 45° C. The aqueous layer was separated from the organic layer using aseparatory funnel. The aqueous layer was thoroughly extracted with hotethyl acetate. The acetate extracts were combined with the originalorganic layer and concentrated on a rotary evaporator to give the triol9 as a white solid material in 91% yield (133 grams). NMR and GCMSanalysis showed the product to be >95% pure. No further purification wasdone. The product was taken directly to the next step (Example 4).

Example 3

This Example serves to illustrate how the sequence of steps leading tothe triol can be altered, in accordance with some embodiments of thepresent invention.

Using a procedure similar to that described in Example 2 (in terms ofquantities, reagents), oleic acid 6 was derivatized to the corresponding9,10-dihydrolyloleic acid which was then reduced with lithium aluminumhydroxide to the corresponding triol derivative 9.

Example 4

This Example serves to illustrate the synthesis of triester 1 from thetriol, e.g., 9. The synthesis of octadecane-1,9,10-triyl trihexanoate 1described below is representative of the synthesis of these types oftriesters.

In a 250 mL 3-neck reaction flask fitted with an overhead stirrer, anitrogen bubbler, and a Dean-Stark trap, 50 grams (0.16 mol) of thetriol 9, prepared as described in Example 2 above, were mixed with 87grams (0.75 mol) of hexanoic acid 12 and 0.9 grams of 85 wt % H₃PO₄ atroom temperature. The resultant mixture was stirred and heated to 160°C. with nitrogen bubbling through it. After 12 hours, the reaction wascomplete, and was cooled to room temperature. The mixture was washedthoroughly with water, dried over MgSO₄ and filtered. The mixture wasdistilled under a vacuum of 100 mm Hg to remove excess hexanoic acid.The desired triester product 1 was obtained in 73% yield (72 grams).Triester species 1 was determined to have lubricant properties as listedin Table 1 (FIG. 4).

7. Summary

In summary, the present invention provides for triester-based lubricantcompositions. The present invention also provides for methods(processes) of making these and other similar lubricant compositions. Insome embodiments, the methods for making such triester-based lubricantsutilize a biomass precursor comprising mono-unsaturated fatty acids,wherein such mono-unsaturated fatty acids are reduced tomono-unsaturated fatty alcohols en route to the synthesis of triesterspecies for use as/in the triester-based lubricant compositions.Subsequent steps in such synthesis may employ carboxylic acids and/oracyl halides/anhydrides derived from biomass and/or Fischer-Tropschsynthesis.

All patents and publications referenced herein are hereby incorporatedby reference to the extent not inconsistent herewith. It will beunderstood that certain of the above-described structures, functions,and operations of the above-described embodiments are not necessary topractice the present invention and are included in the descriptionsimply for completeness of an exemplary embodiment or embodiments. Inaddition, it will be understood that specific structures, functions, andoperations set forth in the above-described referenced patents andpublications can be practiced in conjunction with the present invention,but they are not essential to its practice. It is therefore to beunderstood that the invention may be practiced otherwise than asspecifically described without actually departing from the spirit andscope of the present invention as defined by the appended claims.

1. A method comprising the steps of: a) reducing a mono-unsaturatedfatty acid having a carbon number of from 10 to 22 with a metal hydrideso as to form an unsaturated fatty alcohol; b) epoxidizing theunsaturated fatty alcohol to form an epoxy-alcohol species comprising anepoxide ring; c) opening the ring of the epoxy-alcohol species to form atriol; and d) esterifying the triol with an esterifying species to forma triester species, wherein the esterifying species is selected from thegroup consisting of carboxylic acids, acyl halides, acyl anhydrides, andcombinations thereof, and wherein the esterifying species have a carbonnumber of from 2 to
 18. 2. The method of claim 1, wherein the step ofesterifying the triol with an esterifying species involves a catalystselected from the group consisting of an acid catalyst and a basecatalyst.
 3. The method of claim 1, wherein the step of esterifying thetriol with an esterifying species involves conversion of a fatty acid toan acyl halide species selected from the group consisting of acylchlorides, acyl bromides, acyl iodides, and combinations thereof.
 4. Themethod of claim 1, wherein the step of esterifying the triol with anesterifying species involves conversion of a fatty acid to an acylanhydride species.
 5. The method of claim 1, further comprising a stepof blending the triester species with one or more other ester speciesselected from the group consisting of triesters, diesters, monoesters,and combinations thereof.
 6. The method of claim 1, wherein the triesterspecies is entirely bio-derived.
 7. The method of claim 1, furthercomprising a step of blending the triester species with a base oilselected from the group consisting of Group I oils, Group II oils, GroupIII oils, and combinations thereof.
 8. The method of claim 1, whereinsaid method yields a mixture of triester species by utilizing, in one orboth of steps (a) and (d), reagents that comprise a range of carbonnumber.